Vent holes for altimeter in low power rockets?

Anyone flying altimeters such as the Altimeter 1 or 2 or the Estes altimeter in low power rockets, do you add vent holes?

Yes, absolutely necessary.

3 vent evenly space around the diameter is about all you need. If you have a 3 fin rocket you can use the fins as a way to align the holes. 1/16th - 1/8th is about the size range you want to be in depending on the diameter of the rocket.

yes I use an alt1 in my estes low power rockets, 3 holes I drill em at 7/64(bit smaller then 1/8)

Awesome, thanks for the replies everyone. I guess I'll be taking the drill to my fleet before the next launch!

lol I remember getting my first alt(estes POS)and taking the drill relucltantly to my fleet.....but it has to be done.
Just remember to add the holes before you paint your new kits you want an alt in.:wink:

Remember to seal the edges of the vent holes with CA glue. I remember some of the TARC kids having issues from the "fuzzy" cardboard holes messing up their readings at our local club last year.

Jerome

JeromeK99 said:

Remember to seal the edges of the vent holes with CA glue. I remember some of the TARC kids having issues from the "fuzzy" cardboard holes messing up their readings at our local club last year.

Jerome

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Yes. Drill then CA then drill again to get smooth holes.

Holes MUST be proper distance behind ANY transition or perturbation of airflow.

shreadvector said:

Yes. Drill then CA then drill again to get smooth holes.

Holes MUST be proper distance behind ANY transition or perturbation of airflow.

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How does one figure the "proper distance"?

Every brand of altimeter I have ever seen has instructions.

Those instructions tell you how to use the altimeter and how to install it properly.


Here are the Estes altimeter instructions:

https://www.estesrockets.com/media/instructions/002246_ALTIMETER.pdf

K'Tesh said:

How does one figure the "proper distance"?

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K'Tesh said:

How does one figure the "proper distance"?

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Vent ports like laminar (layered) air flow, so you don't want to put the vent behind transitions or objects that jut out from the airframe. You can use 3 diameters beyond a break plane (e.g., the forward airframe end and the nose cone) as a ROT.

Greg

Love how specific the Estes instructions are... "3 or 4 square or round holes" whatever floats your boat.. er... flies your rocket?

For drilling holes in already painted rockets, should I protect the paint with masking tape or something before drilling?

Only if you plan on holding the rocket in one hand and the drill in another and then turing the drill on and then approaching the rocket with the drill bit and then having the drill bit scracth and dance all along the surface of the rocket.

2:50 would be the time in the video you want:

https://www.youtube.com/watch?v=rzRJWy-3_Dc

XJChris said:

For drilling holes in already painted rockets, should I protect the paint with masking tape or something before drilling?

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For the painted rockets I used a hobby knife and spun the tip against the surface. That made very clean holes.

I used the Altimeter 2 in 3 rockets this weekend. My Corona worked perfectly, my AT Mirage worked great as well, but my Crossfire ISX gave weird readings. The altimeter reported (if I remember correctly) total altitude of 14 feet, velocity of 6 mph, total flight time of 6 seconds. It flew on a C6-5 to way more than 14 feet.

I'm guessing that vent holes were blocked by wadding or parachute or something. Does that sound like the most probable cause?

That is certainly plausible, yes.

XJChris said:

I used the Altimeter 2 in 3 rockets this weekend. My Corona worked perfectly, my AT Mirage worked great as well, but my Crossfire ISX gave weird readings. The altimeter reported (if I remember correctly) total altitude of 14 feet, velocity of 6 mph, total flight time of 6 seconds. It flew on a C6-5 to way more than 14 feet.

I'm guessing that vent holes were blocked by wadding or parachute or something. Does that sound like the most probable cause?

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I just bought an Altimeter2 but haven't had a chance to fly it yet. One thing I've read is you have to be gentle with these altimeters after turning them on. Too much jostling can confuse the sensors and result in inaccurate readings. Your theory on blocking of the ports also sounds possible.